The present invention relates to a portable electronic device and a battery pack, and in particular, to a portable electronic device and a battery pack by which power consumption of cells used therein can be reduced.
Various kinds of portable electronic devices such as portable telephones, portable televisions, portable personal computers, etc. are put on the market. Such portable electronic devices are powered by internal batteries or battery packs which include batteries. In the following, a case of a conventional portable telephone will be described as an example of a portable electronic device, referring to FIG. 1.
As shown in FIG. 1, the conventional portable telephone 1 is powered by a battery pack 2 which includes rechargeable battery cells 2a and 2b, and the battery pack 2 is connected to the portable telephone 1 via feeding terminals 3 and 4.
The portable telephone 1 comprises a radio section 5, an audio processing section 6, a control section 7, a microphone 8, a speaker 9, and an antenna 10.
Circuit blocks such as the radio section 5, the audio processing section 6 and the control section 7 are connected to the feeding terminal 3, and each of them is grounded though unshown, that is, each such circuit block is powered by the battery pack 2. The radio section 5 includes a transmitter section 5a provided with an output amplification circuit, and a receiver section 5b for receiving radio signals from radio base stations. The transmitter section 5a generates a transmitter signal to be transmitted to the radio. base stations, which is a signal with a higher power compared to other signals inside the portable telephone 1. Therefore, the transmitter section 5a needs supply of more power and higher voltage than those needed by other circuit blocks such as the receiver section 5b, the control section 7, etc. In this sense, the transmitter section 5a is a voltage type circuit. Meanwhile, the other circuit blocks such as the receiver section 5b, the control section 7, etc. do not need such high voltages as needed by the transmitter section 5a, since their output signal levels are not large and lower voltage levels for supplying currents of predetermined levels are only necessary. In this sense, the circuit blocks such as the receiver section 5b, the control section 7, etc. are current type circuits.
The battery pack 2 is composed of a plurality of rechargeable battery cells connected in series between the positive pole feeding terminal 3 and the negative pole feeding terminal 4. In the conventional example of FIG. 1, two rechargeable battery cells 2a and 2b are connected in series, and the rechargeable battery cells 2a and 2b supply voltages which are necessary for operations of the circuit blocks in the portable telephone 1 such as the radio section 5, the audio processing section 6, the control section 7, etc.
In such conventional portable telephones as shown above, the output voltage level of the battery pack 2 (i.e. the number of the rechargeable battery cells which are connected in series) is decided according to a voltage level which is necessary for the operation of the portable telephone 1, especially according to a voltage level which is needed by a circuit block which needs the highest voltage. As mentioned above, the transmitter section 5a in the radio section 5 needs the largest power and the highest voltage in the portable telephone 1, for generating the transmitter signal for being transmitted to the radio base stations. Therefore, in the design of the conventional portable telephones, the output voltage level of the battery pack 2 is decided according to the voltage level which is needed by the transmitter section 5a. 
While a telephone call is in progress (i.e. during the talk time), the portable telephone 1 executes transmitting and receiving at the same time. Therefore, the voltage level which is needed by the transmitter section 5a has to be supplied during the talk time. Meanwhile, when the portable telephone 1 is waiting for reception of calling (i.e. during the standby time), the portable telephone 1 executes only receiving, that is, only the receiver section 5b works while the transmitter section 5a is in a state of not working or working at intervals. In such a state where the transmitter section 5a is not working, supply of a lower voltage level which is needed by the other circuit blocks than the transmitter section 5a (such as the receiver section 5b, the control section 7, etc.) is enough for the operation of the portable telephone 1.
However, in conventional portable electronic devices, it is impossible to change or switch the output voltage level of the battery pack according to the operating status of the portable electronic device. In the case of the conventional portable telephone for example, a high voltage which is needed only during the talk time is constantly supplied to each circuit block in the portable telephone 1 even during the standby time, causing power consumption due to the difference between the voltage needed during the talk time and the voltage needed during the standby time.
Generally, the length of the standby time is much longer than the length of the talk time. Therefore, the length of the continuous use time of the portable telephone (i.e. the time between charges of the battery pack) is largely dependent on the power consumption during the standby time, and thus reducing the power consumption during the standby time is greatly effective for extension of the continuous use time length.
It is therefore the primary object of the present invention to provide a portable electronic device by which power consumption is reduced and the continuous use time length of the portable electronic device can be extended.
Another object of the present invention is to provide a battery pack by which power consumption is reduced and the continuous use time length of portable electronic devices in which the battery pack is installed can be extended.
In accordance with a first aspect of the present invention, there is provided a battery pack for containing a plurality of cells which comprises a plurality of switches for switching connection status of the cells between parallel connection and series connection.
In accordance with a second aspect of the present invention, in the first aspect, the battery pack contains a first cell and a second cell, and the battery pack comprises a first wire for connecting the positive pole of the first cell and the positive pole of the second cell, a second wire for connecting the negative pole of the first cell and the negative pole of the second cell, a third wire for connecting the negative pole of the first cell and the positive pole of the second cell, a first switch for connecting/disconnecting the first wire, a second switch for connecting/disconnecting the second wire, and a third switch for connecting/disconnecting the third wire.
In accordance with a third aspect of the present invention, in the second aspect, the battery pack further comprises a fourth wire for connecting the negative pole of the second cell and a negative pole feeding terminal of the battery pack, and a fourth switch for connecting/disconnecting the fourth wire.
In accordance with a fourth aspect of the present invention, in the third aspect, the battery pack further comprises a fifth wire for connecting the negative pole of the first cell and the negative pole feeding terminal of the battery pack, and a fifth switch for connecting/disconnecting the fifth wire, in which both of the fourth switch and the fifth switch are closed when the first cell and the second cell are connected in parallel.
In accordance with a fifth aspect of the present invention, in the second aspect, the first switch and the second switch are switched from open states to close states after the third switch is switched from a close state to an open state when the connection status of the cells is switched from series connection to parallel connection, and the third switch is switched from an open state to a close state after the first switch and the second switch are switched from close states to open states when the connection status of the cells is switched from parallel connection to series connection.
In accordance with a sixth aspect of the present invention, in the fifth aspect, the battery pack further comprises a capacitor for storing electric charge supplied from the first and the second cells and preventing interruption of voltage supply to an electronic device to which the battery pack is attached during the switching of the connection status of the first and the second cells between parallel connection and series connection.
In accordance with a seventh aspect of the present invention, in the second aspect, the battery pack further comprises a control means for controlling the connection status of the cells according to a control signal sent from a portable electronic device to which the battery pack is attached. The control means sets the connection status of the cells in a first status in which the first switch and the second switch are in open states and the third switch is in a close state so that the first cell and the second cell will be connected in series, when the control signal represents an operating status of the portable electronic device in which high voltage is needed. And the control means sets the connection status of the cells in a second status in which the first switch and the second switch are in close states and the third switch is in an open state so that the first cell and the second cell will be connected in parallel, when the control signal represents an operating status of the portable electronic device in which high voltage is not needed.
In accordance with an eighth aspect of the present invention, in the second aspect, the battery pack further comprises a control means for controlling the connection status of the cells according to a control signal which is sent from a portable communication device to which the battery pack is attached. The control means sets the connection status of the cells in a first status in which the first switch and the second switch are in open states and the third switch is in a close state so that the first cell and the second cell will be connected in series, when the control signal represents an operating status of the portable communication device in which communication is needed to be executed. And the control means sets the connection status of the cells in a second status in which the first switch and the second switch are in close states and the third switch is in an open state so that the first cell and the second cell will be connected in parallel, when the control signal represents an operating status of the portable communication device in which communication is not needed to be executed.
In accordance with a ninth aspect of the present invention, in the second aspect, the battery pack further comprises a control means for controlling the connection status of the cells according to a control signal which is sent from a portable communication device to which the battery pack is attached, a first positive pole feeding terminal for supplying voltage to a transmitter section of the portable communication device, a second positive pole feeding terminal for supplying voltage to circuit blocks of the portable communication device other than the transmitter section, a sixth wire for connecting the first positive pole feeding terminal and the positive pole of the first cell, a sixth switch for connecting/disconnecting the sixth wire, and a seventh wire for connecting the second positive pole feeding terminal and the positive pole of the second cell and supplying voltage to the circuit blocks other than the transmitter section constantly. The control means sets the connection status of the cells in a first status in which the first switch and the second switch are in open states and the third switch and the sixth switch are in close states so that the first cell and the second cell will be connected in series and the transmitter section will be supplied with voltage by the series connection of the first cell and the second cell, when the control signal represents an operating status of the portable communication device in which communication by the transmitter section is needed to be executed. And the control means sets the connection status of the cells in a second status in which the first switch and the second switch are in close states and the third switch and the sixth switch are in open states so that the first cell and the second cell will be connected in parallel and the transmitter section will not be supplied with voltage by the first cell and the second cell, when the control signal represents an operating status of the portable communication device in which communication by the transmitter section is not needed to be executed.
In accordance with a tenth aspect of the present invention, in the eighth aspect, the first switch and the second switch are switched from open states to close states after the third switch is switched from a close state to an open state, when the connection status of the cells is switched from series connection to parallel connection. And the third switch is switched from an open state to a close state after the first switch and the second switch are switched from close states to open states, when the connection status of the cells is switched from parallel connection to series connection. And the battery pack further comprises a capacitor for storing electric charge supplied from the first and the second cells and preventing interruption of voltage supply to the portable communication device during the switching of the connection status of the first and the second cells between parallel connection and series connection.
In accordance with an eleventh aspect of the present invention, in the tenth aspect, the control signal includes a communication start signal which represents a status in which the portable communication device is going to start communication, and a standby signal which represents a status in which the portable communication device is in the standby time, and the control means switches the connection status of the cells to the first status before the communication is started, according to the communication start signal, and switches the connection status of the cells to the second status after the communication is stopped, according to the standby signal.
In accordance with a twelfth aspect of the present invention, in the eleventh aspect, the switching of the connection status of the cells by the control means is executed during time slots which are not sent to the portable communication device in the case where the portable communication device to which the battery pack is attached is a device which executes time division communication.
In accordance with a thirteenth aspect of the present invention, in the third aspect, the battery pack further comprises a voltage measurement means for measuring voltage level of the cells. The fourth switch is opened when the measured voltage level is lower than a predetermined voltage level in order to prevent overdischarge of the cells.
In accordance with a fourteenth aspect of the present invention, in the second aspect, the battery pack further comprises a positive pole recharge terminal connected with the positive pole of the first cell, and a negative pole recharge terminal connected with the negative pole of the second cell.
In accordance with a fifteenth aspect of the present invention, in the fourteenth aspect, the first cell and the second cell are connected in series when a charger is connected to the recharge terminals and recharge of the cells is executed.
In accordance with a sixteenth aspect of the present invention, in the fifteenth aspect, the battery pack further comprises a voltage measurement means for measuring recharge voltage level of the cells. Recharge circuit is opened when the measured recharge voltage level is higher than a predetermined voltage level in order to prevent overcharge of the cells.
In accordance with a seventeenth aspect of the present invention, there is provided a portable electronic device containing a plurality of cells. The portable electronic device comprises a plurality of switches for switching connection status of the cells between parallel connection and series connection.
In accordance with an eighteenth aspect of the present invention, in the seventeenth aspect, the portable electronic device contains a first cell and a second cell, and the portable electronic device comprises a first wire for connecting the positive pole of the first cell and the positive pole of the second cell, a second wire for connecting the negative pole of the first cell and the negative pole of the second cell, a third wire for connecting the negative pole of the first cell and the positive pole of the second cell, a first switch for connecting/disconnecting the first wire, a second switch for connecting/disconnecting the second wire, and a third switch for connecting/disconnecting the third wire.
In accordance with a nineteenth aspect of the present invention, in the eighteenth aspect, the portable electronic device further comprises a fourth wire for connecting the negative pole of the second cell and a ground terminal of the portable electronic device, and a fourth switch for connecting/disconnecting the fourth wire.
In accordance with a twentieth aspect of the present invention, in the nineteenth aspect, the portable electronic device further comprises a fifth wire for connecting the negative pole of the first cell and the ground terminal of the portable electronic device, and a fifth switch for connecting/disconnecting the fifth wire. Both of the fourth switch and the fifth switch are closed when the first cell and the second cell are connected in parallel.
In accordance with a twenty-first aspect of the present invention, in the eighteenth aspect, the first switch and the second switch are switched from open states to close states after the third switch is switched from a close state to an open state, when the connection status of the cells is switched from series connection to parallel connection. And the third switch is switched from an open state to a close state after the first switch and the second switch are switched from close states to open states, when the connection status of the cells is switched from parallel connection to series connection.
In accordance with a twenty-second aspect of the present invention, in the twenty-first aspect, the portable electronic device further comprises a capacitor for storing electric charge supplied from the first and the second cells and preventing interruption of voltage supply during the switching of the connection status of the first and the second cells between parallel connection and series connection.
In accordance with a twenty-third aspect of the present invention, in the eighteenth aspect, the portable electronic device further comprises a control means for controlling the connection status of the cells according to a control signal which is generated for representing the operating status of the portable electronic device. The control means sets the connection status of the cells in a first status in which the first switch and the second switch are in open states and the third switch is in a close state so that the first cell and the second cell will be connected in series, when the control signal represents an operating status of the portable electronic device in which high voltage is needed. And the control means sets the connection status of the cells in a second status in which the first switch and the second switch are in close states and the third switch is in an open state so that the first cell and the second cell will be connected in parallel, when the control signal represents an operating status of the portable electronic device in which high voltage is not needed.
In accordance with a twenty-fourth aspect of the present invention, in the eighteenth aspect, the portable electronic device further comprises a transmitter section for executing transmission, and a control means for controlling the connection status of the cells according to a control signal which is generated for representing the operating status of the portable electronic device. The control means sets the connection status of the cells in a first status in which the first switch and the second switch are in open states and the third switch is in a close state so that the first cell and the second cell will be connected in series, when the control signal represents an operating status in which communication by the transmitter section is needed to be executed. And the control means sets the connection status of the cells in a second status in which the first switch and the second switch are in close states and the third switch is in an open state so that the first cell and the second cell will be connected in parallel, when the control signal represents an operating status in which communication by the transmitter section is not needed to be executed.
In accordance with a twenty-fifth aspect of the present invention, in the eighteenth aspect, the portable electronic device further comprises a transmitter section for executing transmission, a control means for controlling the connection status of the cells according to a control signal which is generated for representing the operating status of the portable electronic device, a first positive pole feeding terminal for supplying voltage to the transmitter section, a second positive pole feeding terminal for supplying voltage to circuit blocks of the portable electronic device other than the transmitter section, a sixth wire for connecting the first positive pole feeding terminal and the positive pole of the first cell, a sixth switch for connecting/disconnecting the sixth wire, and a seventh wire for connecting the second positive pole feeding terminal and the positive pole of the second cell and supplying voltage to the circuit blocks other than the transmitter section constantly. The control means sets the connection status of the cells in a first status in which the first switch and the second switch are in open states and the third switch and the sixth switch are in close states so that the first cell and the second cell will be connected in series and the transmitter section will be supplied with voltage by the series connection of the first cell and the second cell, when the control signal represents an operating status in which communication by the transmitter section is needed to be executed. And the control means sets the connection status of the cells in a second status in which the first switch and the second switch are in close states and the third switch and the sixth switch are in open states so that the first cell and the second cell will be connected in parallel and the transmitter section will not be supplied with voltage by the first cell and the second cell, when the control signal represents an operating status in which communication by the transmitter section is not needed to be executed.
In accordance with a twenty-sixth aspect of the present invention, in the twenty-fourth aspect, the first switch and the second switch are switched from open states to close states after the third switch is switched from a close state to an open state, when the connection status of the cells is switched from series connection to parallel connection. And the third switch is switched from an open state to a close state after the first switch and the second switch are switched from close states to open states, when the connection status of the cells is switched from parallel connection to series connection. And the portable electronic device further comprises a capacitor for storing electric charge supplied from the first and the second cells and preventing interruption of voltage supply during the switching of the connection status of the first and the second cells between parallel connection and series connection.
In accordance with a twenty-seventh aspect of the present invention, in the twenty-sixth aspect, the control signal includes a communication start signal which represents a status in which the portable electronic device is going to start communication, and a standby signal which represents a status in which the portable electronic device is in the standby time. The control means switches the connection status of the cells to the first status before the communication is started, according to the communication start signal, and switches the connection status of the cells to the second status after the communication is stopped, according to the standby signal.
In accordance with a twenty-eighth aspect of the present invention, in the twenty-seventh aspect, the portable electronic device is a portable communication device which executes time division communication, and the switching of the connection status of the cells by the control means is executed during time slots which are not sent to the portable electronic device itself.
In accordance with a twenty-ninth aspect of the present invention, in the nineteenth aspect, the portable electronic device further comprises a voltage measurement means for measuring voltage level of the cells. The fourth switch is opened when the measured voltage level is lower than a predetermined voltage level in order to prevent overdischarge of the cells.
In accordance with a thirtieth aspect of the present invention, in the eighteenth aspect, the portable electronic device further comprises a positive pole recharge terminal connected with the positive pole of the first cell, and a negative pole recharge terminal connected with the negative pole of the second cell.
In accordance with a thirty-first aspect of the present invention, in the thirtieth aspect, the first cell and the second cell are connected in series when a charger is connected to the recharge terminals and recharge of the cells is executed.
In accordance with a thirty-second aspect of the present invention, in the thirty-first aspect, the portable electronic device further comprises a voltage measurement means for measuring recharge voltage level of the cells. Recharge circuit is opened when the measured recharge voltage level is higher than a predetermined voltage level in order to prevent overcharge of the cells.